Plug receptacle



Feb. 12, 1929.

W. A. STACEY PLUG RECEPTACLE Filed June '7, 1922 M E TIC N mm 5 m m L m w BIN] ATTORNEYS ,3 ger of shock from touehin Patented Feb. 12, 1929.

UNITEE STATES PATENT OFFICE.

WILLLQK A. STACEY, OF CHICAGO, ILLINOIS, ASSIGNQR TO- THEE BRYANT ELECTRIC COMPANY, OFBlR-IDGEPORT, GONNF-QTIGFT, A CIDBPORAT'IGN OF COIQNEGTICUR,

PLUG RECEPTACLE.

Application filed June 7,

lvly invention relates to plug and the object of my invention in so construct the receptacles and 1 the connections to. the contacts the. it that the danthe shell contact incident, for example, to the insertion or moval of a fuse. plug or the-like, is ininimizei'l. The invention is particularly applicable to receptacles such as are commonly employed cceptacles,

in in used eut-out blocks, but it is also appt .ca-

ble to lump sockets, particularly those oi? the series multiple type.

In the accompanying drawin Fig. 1 is a diagrammatic plan ol :1 double pole .ilordalc branch fuse cut-out illustrating the wiring connections as heretofore commonly established in a. litting of: this type adapted for a three-wire installation;

Fig. 2 a. similar View illustrating, the Wiring connect-ions in accordance with the present invention; I

Fig, 3 is av similar view of a triple pole double branch cut-out block;

Fig. 4 is a similar view of a triple pole, single branch cut-out block;

Fig. 5 is a diagrammatic view similar to Fig. 2 but adapted to a two-wire system;

Fig. 6 is a View similar to Fig. 5 but illustrating a single branch cut-out; and

Fig. 7 is a diagrammatic illustration of the application of my invention to a double branch plug socket.

In house-wiring installations it is common practice to build up the distribution panel from cut-out blocks having receptacles for plug fuses which protect the branch circuits. An example of such a double-branch plug cut-out for a. three-wire system is illustrated in Fig. 1. Such a three-wire system comprises plus and minus mains 10 and 11. respcctively. and a neutral or return main 12, which is grounded. The branch circuit loads 13 and 14 are connected to these leads through plug fuses inserted in the receptacles 15 and 16. i The construction 01 these HQ-UZIHQLl branch blocks is universally that indicated in Fig. 1. inwhich the connections 17 and 18 from the mains are led to the center contacts 20 and 21 of the receptacles, while the connections 22 and 23 to the loads 13 and 14 of the branch circuits are connected to the screw shells 24 and 25 respectively of the receptacles. In order to balance the loads on the mains, the connection is made from one of the receptacles on each side of the block, to

1922. Serial No. 566,450.

the grounded main 12, while the connection to the other receptacle is made on one side of the block to the positive main, and on the ther side, to the negative main.

If the load 14 is too great, one orthe other, or both, of the fuses in the receptacles 15 and 16 will burn out, and to re-establish the circuit it is necessary to inserta new fuse, or new fuses. This i-i'ivolves unscrewing of the fuse plugs from the receptacles and the screwing in of the new plugs, with the consequent possible danger, in both operations, that the attendants fingers may come in contact with the projecting screw shells 2-1 and 25 oi the receptacles. If the fuse in the receptacle 16 is intact While the fuse in the receptacle 15 has been ruptured, the connection from the screw shell 24 of the latter through the branch connections 22-23, shell 25,. fuse in thereceptacle 16, center contact 21 and connection 18 is established to the ground lead 12. Consequently, there is little danger of injury to the attendant even should the lingers touch the screw shell 24 during this operation.

On the other hand, if the fuse inthe receptacle l6 is defective while the fuse in receptaclc 15 is intact, the connection to the screw shell 25 of the reccptaclelG is established with the live main 10 through the receptacle 15, and the load 14. Consequently, if the attendant, during the renewal operation, touches the screw shell 25, the current passes to ground through the attendant and shock results.

The modification of construction which I propose, contemplates the connection of: the screw shells of both receptacles to the ground side of the line, and the connection of the relatively inaccessible center contacts to the live w main. This is illustrated in the doublc branch, two-pole. three-wire system in Fig. This readily accon'iplished by establishing the connection between the ground 12 and the screw shell of one of the pair of receptacles in e ch branch circuit, instead of following the usual practice of connecting the ground to the center contac of that receptacle. lVhen this arrangement is employed it is clear that 7 contact with the screw shell of any of the receptacles results in no danger of shock, since all are grounded. Thus, not only may the grounded shell 25 of receptacle 16 be safely touched, but if the fuse in receptacle 15 is defective and must be renewed, While the fuse in receptacle 16 is intact, the screw shell 2 of receptacle 15 is nevertheless connected to ground through the fuse in the receptacle 1.6.

The same idea may he carried out in a double-branch, three-pole, threeovire system, as shown in F 3. In this modification t leads from the e plus and ininus'ina and 11 are connected to the center contacts 26 and 27 of the receptacles balanced on opposite sides or the circuit, while the connectie i from the load 28 is returned through the c ter contact 29 of its :tuse receptacle conn cted through the cooperating screu shell 80 to the ground main 1%. It is obvious that the screw shells 31 and of the receptacles, the center contacts or which are connected to the power lines 10 and 11, are always grounded through the return branch 33.

In Fig. 4 the some arrangement is indicated for a single-branch, triple-pole, three- Wire cut-out block.

In Fig. 5 the same idea is en'ibodied in a. two-wire, double-branch cut-cu As will be seen, the connection tron) the hvc main 13s is established to the center contacts 35 on one side of the branch line, while the ground line 36 is connected to the screw shells 3'? of the receptacles on the return side the branch circuit.

The same thought is applied in 6 to the single-branch, double-pole, two-Wire cute out.

As above mentioned, the invention is plicahle also to nnilti-lainp-socket fittin where the sockets are arranged in series. have indicated in Fig. 7 a twin plug soche' embodying the idea; The screw shell 38 0' the plug is indicated as connected to ground,

and the center contact 39 to the incoming live wire. The connection from the center contact 39 of the plug is estahlishedto the center contact &0 of one receptacle, and from the shell 41 of the latter to tne center contact &2 of the second receptacle, while the screw shell 43 the latter is connected to the grounded screw shell 38 of the plug. It is thus obvious that the screw shells of both lamp sockets are connected to ground and may be touched by the attendant without dangerot shock.

The idea may be applied to various other i those illustrated heii'ig inerely illus- 1 LIVE cinhodin'ients of what I claim as my nvention. l have not shown any particular structure for establishing these connections, since this is subject to many n'iodii'ications well understood by those skilled, in the art.

I clai1n' QlOCil'lC wiring system having a group ct feed 111 i one of which is grounded, an electric cut-out block having an insulating V1 ILL AM A. STACEY. 

